GAMEDATA.CFI unpack

import os
import struct
import gzip

def ensure_dir(path_name):
    if not os.path.exists(path_name):
        os.makedirs(path_name)

TOC = []
with open('GAMEDATA.CFI', 'rb') as f:
    folders = ord(f.read(1))
    for folder in range(folders):
        size = ord(f.read(1))
        folder_name = f.read(size).decode('ascii')
        files = ord(f.read(1))
        if files == 0xFC:
            files = struct.unpack('<H', f.read(2))[0]
        for file in range(files):
            size = ord(f.read(1))
            file_name = f.read(size).decode('ascii')
            offset, size = struct.unpack('<II', f.read(8))
            TOC.append((folder_name, file_name, offset, size))
    base_pos = f.tell()
    for folder_name, file_name, offset, size in TOC:
        ensure_dir(folder_name)
        path = folder_name + file_name
        f.seek(base_pos + offset)
        with open(path, 'wb') as g:
            if file_name[-4:] in ('.txt', '.dat', '.PNG', '.sbk'):
                g.write(f.read(size))
            else:
                zsize = size - 4
                size = struct.unpack('<I', f.read(4))[0]
                g.write(gzip.decompress(f.read(zsize)))